00:05 welcome to this series on computer
00:08 networks and the purpose of this series
00:10 is to provide you with the kind of
00:12 information that you need so that you
00:14 feel competent in terms of diagnosing
00:18 and resolving issues that might pop up
00:24 networks so the first thing that we need
00:26 to address is what is a computer network
00:30 in other words we need to come up with a
00:34 definition and for our intents and
00:37 purposes a network is a group of
00:40 electronic devices that we are going to
00:42 connect together in some shape or form
00:45 so that we can facilitate the kind of
00:47 communication between them and the kind
00:50 of sharing of resources between them
00:55 want now there are few benefits of this
00:58 and I'll just highlight three
01:00 and this list is by no means
01:03 exhaustive so what are the three
01:06 benefits that we are going to look at
01:08 one networks allow us to transmit and
01:12 data and when we say data we're talking
01:15 about images so you can think about
01:17 Instagram for example we're talking
01:20 about text so you can think about emails
01:23 or you can think about
01:24 WhatsApp we're talking about audio you
01:28 can think about spotty
01:30 or you can think about WhatsApp as well
01:33 and you can share video we're talking
01:35 about like a YouTube we're also talking
01:37 about WhatsApp once
01:40 more so that's the benefit we can
01:43 transmit data and we can receive data so
01:47 benefit another benefit is that we can
01:51 resources and the resources can be
01:53 Hardware resources like a printer for
01:56 example so we have an office
02:00 and we have several persons within the
02:02 office who are sharing a single
02:06 printer but it can also be digital
02:08 assets that we are sharing for example
02:11 files so those assets that we spoke
02:14 about earlier like images and audio and
02:16 video and so on those can also be
02:19 shared additionally we can share
02:22 applications which are programs that are
02:24 going to carry out particular
02:26 functionality so we can share
02:28 applications as well
02:31 so the second benefit here is that we
02:35 resources and the third
02:37 benefit is that we can save time and we
02:42 cost so in terms of sending data we can
02:46 save time because when we send it over
02:49 the network it is transmitted let's say
02:54 instantaneously so there's very little
02:56 delay between the time that it is sent
02:58 and the time that it is rece
03:01 received if we compare this with
03:04 traditional methods that used to exist
03:06 such as the post office then we can see
03:10 the amount of saving in terms of time
03:13 that we are achieving because when we
03:15 send the email it is sent
03:17 instantaneously but if we were to post a
03:20 letter it might not reach until two
03:22 weeks 3 weeks down the
03:24 line so we're able to save
03:28 time the the other thing that we are
03:32 cost so going back to that example about
03:36 printer it is going to be very costly to
03:39 put a printer on every Dex within an
03:42 office if we assume that the office has
03:46 persons then that would mean we would
03:50 printers the challenge with this is that
03:53 the printers are not going to be used
03:57 247 so when I put a printer on every
03:59 everybody's decks it is not as if
04:01 they're going to be using that printer
04:03 continuously throughout the
04:05 day so it would therefore be better if I
04:08 could buy one printer and find a way to
04:11 share it among these 10
04:14 individuals and the good thing is that a
04:17 computer network facilitates this kind
04:20 of sharing and in so doing we can cut
04:23 down on cost because instead of having
04:26 to buy 10 printers we can now buy one
04:32 it so we have looked at what a network
04:36 is and we have looked at a few benefits
04:39 which are offered by the
04:42 networks it is now time therefore to
04:45 dive into the architecture of a network
04:52 operate and on the screen we have an
04:56 example of a network this is a simple
05:00 and for all intents and purposes we can
05:02 call it a peer-to-peer
05:05 Network we have two PCS or two computers
05:10 and we have labeled them for convenience
05:12 so we have PC one and we also have PC
05:18 too these computers are connected via
05:23 wire as denoted by this dotted line that
05:31 above the machines you will realize that
05:34 there's a I'm going to call it a
05:39 192168101 for pc1 and
05:48 PC2 these numbers are going to be unique
05:51 for each device that is on the
05:55 network and these numbers these unique
05:58 configuration numbers is known as an IP
06:03 address and this is the first thing that
06:05 I want you to bear in
06:07 mind every device that is going to be
06:10 able to communicate on the network that
06:13 is able to transmit and receive data on
06:15 the network needs to have an IP
06:20 address and as mentioned before that IP
06:23 address has to be unique within the
06:26 network we'll talk about this a little
06:30 in a in a deeper way or more fullsome
06:34 way the other thing that you'll find
06:37 below the computers is that there's
06:39 another number there that kind of looks
06:41 strange this number is expressed in
06:47 way there are some knowledge that you
06:50 need to bring into this series for
06:54 example binary you need to be
06:56 comfortable with binary information and
06:59 how to convert from binary to octal and
07:02 how to convert from binary to
07:04 hexadecimal and vice
07:07 versa because that information is going
07:09 to be critical in terms of understanding
07:12 some of the things that we are going to
07:16 discuss suffice it to say that we have a
07:21 number at the below each
07:26 computer and this heximal number is also
07:30 need and this is called the MAC
07:34 address once again we are going to dive
07:36 a bit deeper into what Mac addresses are
07:39 where they are found and what is their
07:42 purpose or significance in terms of the
07:46 network so we have a basic network two
07:50 computers they are connected via a wire
07:53 and we now want to see if they can
07:57 communicate with each other now the tool
08:00 that we are using in this case is Cisco
08:03 Tracer which is a simulator and I
08:07 encourage you to download it for
08:09 register it and to make use of it in
08:13 terms of duplicating these networks that
08:16 we are going to be using as
08:19 demonstration and we are using these
08:21 demonstrations because it will provide
08:26 better understanding of what is
08:28 happening to the network
08:34 network so the challenge now is how do I
08:37 determine whether or not pc1 is able to
08:42 PC2 and I'm going to go to
08:46 the well I'm going to go to pc1 I'm
08:49 going to open up the configuration tools
08:53 and I'm going to go to the desktop
08:56 utility and on the desktop utility I'm
08:59 going to make use of the command
09:02 prompt remember this is a
09:04 simulation and it's simulating pretty
09:07 much based on the Windows platform so
09:10 whatever we are doing here you can do
09:12 something similar on your machine once
09:14 you load a command prompt and that is
09:18 assuming that you are making use of a
09:22 box if it is that you're making use of a
09:25 Linux box or a Mac for example then
09:29 there's also some feature there that
09:31 will allow you to open a command prompt
09:34 and to execute similar commands so it
09:37 won't be the same the names might be
09:39 different but what you get when you
09:42 execute these comparable commands is
09:45 going to be the same kind of
09:49 information I'm going to click on the
09:54 Windows there's a command called
09:57 ping and and the purpose of ping is to
10:01 allow us to try and
10:03 communicate with another device that is
10:06 network so I am on pc1 you look at the
10:10 top here you realize I am on
10:13 pc1 and pc1 has an IP address of 1
10:22 but I want to communicate with
10:25 PC2 and PC2 has an IP address of 192 .1
10:30 68102 so that's what I'm going to
10:38 put in the command window so I want to
10:45 192.168.1.2 and I'm going to Ping it by
10:49 making reference to its IP address I'm
10:57 enter and you're seeing that it is
10:59 sending over some data it says 32 bytes
11:03 data and we are getting a response from
11:07 the from PC2 which is 1
11:12 192.168.1.2 and then it gives us some
11:15 statistics at the end we sent four
11:17 packets this term packet is going to
11:20 become important as we dive deeper
11:23 into the content but suffice it to say
11:26 that four packets were sent
11:29 and four packets were received which is
11:31 good it means that we lost none of the
11:34 data so the Lost is equal to
11:37 zero and this tells us that we are able
11:44 PC2 or to rephrase pc1 is able to
11:57 PC2 we can also do it from from the
11:59 reverse can PC2 communicate with
12:02 pc1 so once again we are going to click
12:07 desktop open the command
12:11 prompt and this time we are going to
12:14 pc1 remember we need to know the IP
12:17 address of the device that we are going
12:19 to communicate with and in this case it
12:26 so we are on PC two and we want to
12:33 pc1 we hit enter once again 32 bytes of
12:38 data has been sent and we realize that
12:41 we're now getting a response from
12:49 192.168.1.1 four packets were
12:52 sent four packets were received we have
12:56 a 0% loss so all the data
13:04 properly so we have these IP addresses
13:08 that were configured onto this these
13:11 machines and by the way these were
13:15 configured manually which means I am the
13:18 person who put them
13:21 on how did I put them
13:29 you will realize that there's something
13:31 here that talks about fast
13:33 ethernet click on it and you will
13:36 realize that in this section that says
13:39 ipv4 which means IP version 4 I have
13:45 placed the IP address there so that's
13:51 192.168.1.2 because we are on PC too so
13:55 if I wanted to change this for example I
14:00 10 and if I exit the
14:03 screen and I go back
14:06 in and go back to the fast ethernet then
14:10 you realize that it now says 1010 at the
14:13 end I want it to be two so let me change
14:19 two and we are going to ensure that that
14:26 safe now you might be wondering why am I
14:31 ethernet well whenever we are using
14:35 connections and in this case I have a
14:38 wired connection then the most prevalent
14:42 protocol that is being used is the
14:44 ethernet standard so those cables that
14:47 you plug the back of your
14:51 machine um they all operate on the
14:56 protocol so that's why we are setting up
14:59 the IP addresses on the fast ethernet
15:03 interface once again this term interface
15:06 we will talk about it more in depth as
15:09 we dive deeper into the
15:12 course so our aim right at this stage is
15:17 just to show that we can create a
15:19 network we can have the computers or the
15:23 devices communicate over the network and
15:27 also illustrating or highlighting the
15:30 point that the concept of an IP address
15:36 important and this IP address
15:40 for in most instances has to be
15:43 configured so it's either going to be
15:45 configured by you manually or you're
15:48 going to set it up so that it can be
15:51 automatically by the network and that
15:55 will take us into this protocol above
15:57 here that talks about DH
16:01 CP we talk about that a bit later in
16:06 depth so another thing that I want to
16:08 illustrate here is that we can find out
16:13 information about each of these machines
16:16 so let me go back to the
16:18 desktop and I'm going to issue a command
16:21 called ip config once again remember
16:25 we're talking about a Windows machine so
16:29 I am on PC2 I'm going to issue ip config
16:33 and we're going to have a look at what
16:34 it gives us in terms of a
16:37 response so when I look at ip config and
16:43 V4 section which is right here then you
16:47 realize that the IP address is the same
16:49 thing as I had mentioned before it is
16:53 192.168.1.2 which is the same IP address
16:56 that I had configured manually
17:00 you'll also see something that talks
17:03 about IP V6 there are two versions of Ip
17:06 addressing schemes we have version four
17:10 which is the traditional one and we have
17:12 version six which is the new
17:15 one but for most intent and purposes we
17:19 are going to be focusing focusing on IP
17:24 for so this takes care of the IP
17:28 but remember I had also mentioned that
17:31 there is a number below the machines
17:33 which is the MAC address that is also
17:36 going to be important so how do we find
17:42 address well going back we can use a
17:47 config but we're are going to use it
17:51 option and we put the forward slash and
17:54 we put all which means I want to run the
18:02 to make use of an option that gives me
18:05 all the information that IP config has
18:14 enter then you will realize that we
18:17 still have the version for information
18:21 in terms of IP address but we also have
18:24 something here that is called a physical
18:26 address and if you look at that number
18:32 eb7 E5 4B and you map it back to this
18:37 number that you seeing here on PC2 or
18:41 below PC you will realize that it is the
18:46 number now this number is there
18:51 because the fast ethernet interface and
18:55 notice right here it says fast ethernet
19:02 component physically comes with an
19:05 address that is burnt into it or built
19:08 into it and that address or that number
19:13 uniquely identifies that particular
19:18 interface so therefore when we have a
19:21 look at the IP config information there
19:26 are two things that are important for us
19:29 networking at this level we are
19:32 interested in the physical address or
19:33 the MAC address and we are also
19:36 interested in the IP address and
19:39 specifically the version 4 address so
19:42 those are the two pieces of
19:45 information that you're looking
19:49 for so that takes care of what we want
19:52 to cover in this first session of the
19:56 series and in the next session in the
19:59 series we're going to have a look at
20:03 troubleshooting in relationship
20:05 to the peer-to-peer Network that we have
20:08 created here and see some of the issues
20:11 that we can have and how to resolve
